The invention relates to a method and apparatus for controlling the driving dynamics of a vehicle equipped with an ABS system, where the braking pressure is varied (when the wheels exhibit an impending lockup) in order to prevent excessive wheel slippage.
For early avoidance of critical situations, it is advantageous in many driving situations to intervene in the handling of the vehicle (via a control or control system) depending on parameters of a specific driving situation. A number of products on the market use known embodiments of the present method.
Contrary to the prior art, however, it is an object of the present invention to provide a method for controlling the driving dynamics of a vehicle that also detects in a simple manner borderline situations regarding the tipping stability of motor vehicles.
This and other objects and advantages are achieved by the apparatus according to the invention, in which a method for controlling the driving dynamics of motor vehicles (especially commercial vehicles) is implemented when the brakes exhibit a tendency to lock up to vary the brake pressure in order to avoid excessive wheel slippage (detected by an ABS control system) and a decrease in the stability of the vehicle when negotiating a curve.
In an embodiment of the invention, additional software for the ABS system is provided, so that a decrease in the roll-over stability of the vehicle when negotiating a curve is detected using the ABS system.
The invention is therefore advantageously suitable for avoiding dangerous situations in which a vehicle (especially a commercial vehicle) threatens to tip over. In the specific case of commercial vehicles, with a correspondingly high positive contact between the road and the tires, the vehicle can also tip over instead of rounding the curve. The present invention detects this situation (in a surprisingly simple manner) by using an ABS control procedure during a brake application when negotiating a curve.
In an especially advantageous improvement on the invention, for example, an automatic braking system, if the driver applies the brakes lightly when rounding a curve (so lightly that lockup caused by ice, for example, cannot occur), the lockup of the wheels is used to trigger a warning signal or a stabilizing intervention in the handling dynamics of the vehicle, since lockup of the wheels (in this case) indicates that the vehicle is slightly lifting the corresponding wheels off the ground.
Activation of the ABS system can be detected electronically, for example. Additional expensive sensors are not required; only the transverse acceleration can be detected, for example, via a sensor suited for the purpose. To increase driving stability, when a decrease in tipping stability is detected, control of the handling dynamics can be triggered to increase the roll-over stability of the vehicle. An especially advantageous application of the invention is in the commercial vehicle area, because it is precisely in this case that accidents happen as a result of the vehicle tipping over on curves, or when violent steering movements are made in response to a dangerous situation.
Another critical advantage of the invention is in the case of a combination vehicle composed of a tractor and a trailer. Here, the software and/or hardware for control need only be installed on the tractor. As a result, the invention can then be used on all vehicles that pull trailers equipped with ABS systems (semitrailers for example) without the trailer's ABS system having to be equipped with special additional devices related to handling dynamics. The cost of the trailer's ABS system is unaffected by the invention. In addition, a tractor equipped with a device for implementing the method according to the invention can be combined with a wide variety of trailers regardless of their ABS systems.
It is also especially advantageous if it is initially determined on the basis of a suitable parameter (for example, transverse acceleration) that the vehicle is rounding a curve and thus a dangerous situation has developed. Here, a slight ABS intervention is automatically launched (in an air brake system of a truck, for example, braking at 0.5 bar) which has almost no effect on the handling of the vehicle. Nevertheless, if an ABS control process is launched in such a situation, it is highly probable that the problem is not one due to the wheels locking up because the road is icy, but rather the problem is a lockup caused by a particular wheel lifting off the road. In this case, for example, warning signals are displayed to the driver and/or a brake application is triggered to reduce the transverse acceleration or another suitable intervention is made in the handling dynamics (throttling the engine or steering).
Embodiments of the invention will be described in greater detail below with reference to the drawings.